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 golriz June 28, 2013 16:17

*****Easy Question*****

Hello everybody,
I should to model 3 different phases (water, solid particles and air) in a hydraulic structure. On the other hand, how can I model a free surface flow of water and solid particles?
Can I model this problem by using star ccm+? If I can, which model must be applied?
Is it possible to apply Eulerian model for simulating of liquid-solid phase?
I hope someone could help me.
Regards,

 siara817 June 29, 2013 03:35

Yes you can model whatever you said. You need to read the tutorial for Eulerian multiphase, you need to define phases, air, solid particles and water. If you have a tank of water, then you may need to use VOF. I recommend you to read tutorial or explain in detail your simulation case.

 golriz June 29, 2013 04:37

Hi Siamak and thanks for replying. Yes, I have a tank of water and solid particles (sediment). The tank is being used for trapping medium to coarse sediment particles by settling. Water and solid particles inflows to the tank and most of particles are deposited in the tank and a small percentage of particles with water are exited from the outlet of the tank. It should be noted that the flow in the tank is free surface. Now, which model is appropriate for this case? Eulerian or VOF? Can VOF approach be used for solid particles modeling?
Best Regards,

 siara817 July 1, 2013 05:12

Hi golriz,

It is a little tricky, when you have a free surface. You have three phases air, water and solid particles. By VOF you can simulate the case of water-air and with DEM you can show the settlement of solid particles in water. I think try one of them and see if it is possible to add the other phase.
For DEM look at this tutorial DEM: Particle Settling.

 golriz July 1, 2013 14:51

I have another question. Can I model both free surface and settling of solid particles by using Eulerian model? Or by Eulerian I can not predict the free surface?

 siara817 July 2, 2013 03:33

To predict the free surface, you need to use VOF. I tried yesterday to test if it is possible to run the Lagrangian multiphase together with VOF. It was possible to select, but I could not see the Lagrangian solver to run. I suggest you to learn first how to run a VOF work on the particle phase. If I found any new thing, I will inform you.

 siara817 July 2, 2013 04:17

Hi golriz,
I used VOF to simulate water and air and then I added a Lagrangian phase for solid particles. It works for steady state case. For transient, it did not work I do not know why.

 golriz July 2, 2013 10:50

Thanks a lot for suggestion. I try also to model the free surface by Eulerian model, but the solution was diverged.

 siara817 July 3, 2013 05:51

Change the physics to be first order. After iterating until the residual gets uniform, then change one by one to second order.

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